离子液体中纤维素-甲基丙烯酸羟乙酯的均相聚合

在离子液体介质中利用原子转移自由基聚合方法合成了纤维素-甲基丙烯酸羟乙酯的接枝共聚物,采用甲基丙烯酸羟乙酯单体合成纤维素聚合物,并对聚合物进行结构测定与性质分析。通过FTIR、1HNMR和GPC对聚合物结构及相对分子质量(简称分子量,下同)进行分析,研究了不同溶剂对聚合条件、接枝效率的影响,以及在不同溶剂中聚合物的结构、分子量分布、热稳定性及形态有何变化。结果表明,在溶剂N,N-二甲基甲酰胺(DMF)中进行的反应聚合速率及终止速率均高于在丁酮中进行的反应。纤维素接枝甲基丙烯酸羟乙酯聚合物分子量分布约为1.81,该聚合物热稳定性较强;在DMF中呈球状颗粒,平均直径50 nm;在选择性溶剂丙酮中颗粒直径100 nm左右。     

离子液体中纤维素-甲基丙烯酸羟乙酯的均相聚合

在离子液体介质中利用原子转移自由基聚合方法合成了纤维素一甲基丙烯酸羟乙酯的接枝共聚物,采用甲基丙烯酸羟乙酯单体合成纤维素聚合物,并对聚合物进行结构测定与性质分析。通过FTIR,1H-NMR和GPC对聚合物结构及分子量进行分析,研究了不同溶剂对聚合条件与接枝效率的影响,以及亲水基团的引入聚合物的结构、分子量分布、热稳定性以及在不同溶剂中的形态有何变化。结果表明:在溶剂DMF中进行的反应聚合速率及终止速率均高于在丁酮中进行的反应。纤维素接枝甲基丙烯酸羟乙酯聚合物分子量分布在1.81左右,该聚合物热稳定性较强; 在DMF中呈球状颗粒, 平均直径50nm,在选择性溶剂丙酮中颗粒直径100nm左右     

杂质对合成中乙烯基聚丁二烯橡胶的影响 Ⅰ.水对聚合的影响

以正丁基锂为引发剂,环己烧为溶剂,采用四氢呋喃或二乙二醇二甲醚为结构调节剂的条件下,研究了聚合体系中水对合成中乙烯基聚丁二烯的聚合速度、转化率以及聚合物微观结构、特性粘度和分子量分布的影响。 研究结果表明,体系中水的存在,不影响聚合物微观结构(添加THF体系)、聚合速度、单体浓度的级数和表现增长活化能,但影响聚合转化率、聚合物微观结构(添加2 G体系)和特性粘度。     

低分子量聚N-乙烯基甲酰胺-co-乙烯胺的合成

以N-乙烯基甲酰胺为单体,N,N-二甲基甲酰胺和乙酸乙酯为混合溶剂,偶氮二异丁腈为引发剂,十二硫醇为链转移剂,通过沉淀聚合法制备了低分子量的聚N-乙烯基甲酰胺。详细研究了单体质量分数、混合溶剂配比、引发剂用量、链转移剂用量、反应温度及反应时间对聚合反应的影响。在最佳聚合条件下,聚合物收率可达93.1%、聚合物的数均分子量(Mn)为2 975.2,PDI=2.64,且聚合残液可循环利用。然后将所得聚合物在酸性条件下水解,制备了不同胺化度的聚N-乙烯基甲酰胺-co-乙烯胺,产品的数均分子量为1 000~1 400,PDI为1.34~1.40。     

溶液聚合制备油溶性减阻剂中溶剂的选择和聚合产物性能的表征

依据溶度参数理论预测溶剂和聚合物的相容性,为合成具有更高分子量的减阻聚合物提供理论指导。实验结果表明,使用脂肪烃溶剂（正己烷、正辛烷和环己烷）和芳香烃溶剂（甲苯、苯和氯苯）合成减阻剂黏均分子量的大小顺序与依据溶度参数理论预测不同溶剂合成减阻剂的分子量大小顺序吻合。脂肪烃溶剂是α-烯烃聚合的良溶剂,芳香烃溶剂是α-烯烃聚合的不良溶剂。良溶剂中环己烷是α-烯烃聚合的最佳溶剂,易合成分子量较大的减阻剂。同时,通过室内环道评价装置及XRD和1H-NMR测试手段对聚合产物的结构和性能进行了表征。     

聚合条件对稀土顺丁橡胶分子结构的影响

研究了丁二烯在三异丁基铝-环烷酸镨钕富集物—氯二异丁基铝催化体系中的聚合。考察了各种聚合条件对聚合物分子量及其分布的影响。通过调整催化剂用量、单体浓度、聚合温度等因素,可使聚合物的特性粘度在3—10之间变化,而且发现催化剂浓度及单体浓度均与聚合物分子量呈线性关系。     

吡啶基三唑配合物催化下甲基丙烯酸甲酯的原子转移自由基聚合研究

以配体3,5-二-(4-吡啶基)-1,2,4-三唑与CuX形成催化剂,分别以α-溴代异丁酸乙酯和氯化苄为引发剂,环己酮为溶剂,进行了甲基丙烯酸甲酯(MMA)的原子转移自由基聚合(ATRP),同时考察了配比、溶剂量以及温度对聚合速率、聚合物分子量及分子量分布的影响.80℃下的聚合反应速度高于70℃;以环己酮为溶剂,单体与溶剂之比为1∶1.5时可得到较低分子量分布的聚合物.实验结果表明以吡啶基三唑为配合物催化甲基丙烯酸甲酯的聚合过程中,转化率和分子量随时间的增加而增大,聚合反应符合一级动力学规律,所得聚合物分子量分布较窄(1.21～1.46),结合端基分析和扩链反应结果,证明该聚合反应符合"活性"/可控自由基聚合.     

天然氨基酸作用下ε-己内酯的微波开环聚合反应

研究天然氨基酸作用下ε-己内酯在微波场中的开环聚合反应.在微波聚合中,微波功率、反应时间、氨基酸的浓度等对聚合反应有显著的影响,在微波功率510 W、ε-己内酯与L-笨丙氨酸摩尔比等于60、反应时间4 h的条件下,可得到重均分子量(-Mw)为13.3 kg/mol的聚(ε-己内酯).红外(FTIR)和核磁共振(1H-NMR)分析证实氨基酸连接到聚合物链上.     

水性体系用颜料分散剂的分子量及分子量分布的控制

采用自由基聚合和稳定自由基聚合,可合成水性体系用的颜料分散剂。介绍了低聚合度、窄分子量分布的聚合物分散剂的控制方法。引发剂、链转移剂、单体的浓度、溶剂种类、反应方式、温度等诸因素对分散剂的分子量和分子量分布有很大影响。讨论了诸因素对分散剂分散性的影响。     

聚磷腈的合成及应用研究进展

介绍了聚磷腈及中间体聚二氯磷腈的制备方法:聚磷腈由聚二氯磷腈和亲核取代试剂发生亲核反应制备;聚二氯磷腈由热开环和活性阳离子两种聚合法制备,热开环法又分为溶剂聚合、原位聚合和三氯化磷法。溶剂热开环聚合法由于获得的聚合物分子量分布较窄、分子量大和工艺条件温和等优点,适合于工业化制备。较全面地总结了聚磷腈在阻燃材料、生物医用材料、导电材料、膜材料等领域近期的研究进展和发展趋势。     

Microwave-Irradiated Ring-Opening Polymerization of Octamethylcyclotetrasiloxane in the Presence of Water

α, ω-dihydroxyl polydimethylsiloxane (DHPDMS) was prepared via anionic ring-opening polymerization of octamethyl cyclotetrasiloxane (D₄) under microwave irradiation (MI) in the presence of water. The conversion and polymerization rate were calculated by the gravimetric method. The effect of microwave power on the polymerization was investigated. FTIR was used to verify the DHPDMS prepared at different irradiation times. The results show that the conversion is the highest when the initial microwave power is preset at 700 W. Compared with conventional heating (CH), the polymerization rate and equilibrium conversion are both enhanced by the introduction of microwave irradiation. The species and concentration of the cyclosiloxane mixture caused by backbiting reaction were determined by gas chromatography/mass spectrometry (GC/MS). The lower concentration of cyclosiloxane in the polymer prepared under MI indicates that side reactions have been reduced and a pure polymer obtained. The molecular weight and polydispersity index (PDI) measured by GPC show that under MI, the molecular weight of DHPDMS is lower and PDI is narrower than those under CH.     

196~#不饱和聚酯的微波合成

采用微波合成技术制备了196#不饱和聚酯,考察了微波功率、辐射时间和催化剂质量分数等对产物性能的影响。结果表明,最佳合成条件为微波功率325W、辐射时间20min、催化剂质量分数0.350%,在此条件下所得196#不饱和聚酯的重均分子量为10332,相对分子质量分布为2.639,且反应速率提高了24倍,能耗显著降低。     

196#不饱和聚酯的微波合成

采用微波合成技术制备了196^#不饱和聚酯,考察了微波功率、辐射时间和催化剂质量分数等对产物性能的影响。结果表明,最佳合成条件为：微波功率325w、辐射时间20min、催化剂质量分数0．350％,在此条件下所得196^#不饱和聚酯的重均分子量为10332,相对分子质量分布为2．639,且反应速率提高了24倍,能耗显著降低。     

Evolution to similarity solutions for polymerization and depolymerization with microwave radiation

The kinetics of polymerization and depolymerization are critical in understanding the stability and characterization of polymers. The kinetics of simultaneous polymerization and degradation of poly(methyl methacrylate) have been investigated by varying the initiator concentration and monomer concentration under the influence of microwave energy. Microwave radiation initially polymerizes the monomer, then degrades the resulting polymer and the polymer attains an equilibrium molecular weight distribution with a polydispersity of two. To understand more fully the kinetics, the molecular weight distribution (MWD) is represented as a gamma distribution; the random degradation rate coefficient is assumed to vary linearly with molecular weight and the polymerization rate coefficient is assumed to be independent of molecular weight. The change of the MWD with time is studied by continuous distribution kinetics; the solutions obtained depict the change of the average molecular weight, polydispersity and the gamma distribution parameters with time. Experimental data indicate that reaction rates are enhanced by microwave radiation and the MWD approaches a similarity solution within 10 min for all the investigated cases. The model satisfactorily predicts the change of the MWD with time. © 2001 Society of Chemical Industry     

Spectrofluorometric analysis and electrical conductivities of styrene and methyl methacrylate polymers

Conductive polymers were obtained by using a new polymerization method where UV‐light was used as a photochemical initiator. To obtain high molecular weights, optimum irradiation times were determined. The luminescence properties of polymers have been found to be useful for their identification. The use of luminescence spectroscopy as an analytical technique for polymer identification involves the measurement of fluorescence emission spectrum, which is obtained by exciting the polymer with UV‐radiation. Fluorescence emission spectra of polystyrene (PS) and polymethyl methacrylate (PMMA) samples were taken at room temperature at excitation wavelengths at 290 nm and 292 nm, respectively. PPMA was prepared with different molecular weights, and the intensity of the fluorescence emission was correlated with polymer chain length. Conductivity versus molecular weight relation was established for each polymer. The plots obtained between conductivities and molecular weights can be used as a calibration curve. From the plot of emission intensity against polymer molecular weights, the molecular weights of unknown polymeric samples can be determined. The most efficient irradiation times were determined by using conductivity versus irradiation time plots. Conductivity versus temperature change of the polymeric samples at different temperatures was determined. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

环状碳酸酯的合成及微波开环聚合研究

以2,2-二甲基-1,3-丙二醇和氯甲酸乙酯为原料合成了环状碳酸酯5,5-二甲基-1,3-二口恶烷-2-酮(DTC),并对DTC在食品添加剂乳酸锌引发下的微波开环聚合进行了研究.结果表明:在170 W的微波辐照下,辐照时间对聚合物的分子量有较大影响,当辐照时间为17 min时,聚合物的分子量达到最大,Mw、 Mn分别达到208 000和127 000.     

Directional polymerisation and electronic properties of a cyanosubstituted dialkylpolyphenylenevinylene

Summary The synthesis of a monomer allowing for directional polymerisation based on the Knoevenagel condensation reaction is presented. The free running polymerisation gave a molecular weight (M _w = 24650 g mol^-1) polymer product. The polymerisation reaction could be followed by size exclusion chromatography (SEC) and the molecular weight of the polymer product could be controlled by termination of the polymerisation reaction at a suitable time. When terminated before completion a lower molecular weight product was obtained that could be separated into oligomers using preparative SEC. The polymer product and the oligomers were found to have very similar physical properties in terms of the optical band gaps, electronic energy levels and charge carrier mobilities as studied by UV-vis and pulse radiolysis time resolved microwave conductivity (PR-TRMC). Finally the positions of the filled energy levels were determined using ultraviolet photoelectron spectroscopy (UPS).This revised version was published online in September 2004. Due to technical problems, the previous version contained an incomplete PDF.     

Synthesis of new polyethers derived from isoidide under phase‐transfer catalysis: Reactivity and selectivity under microwaves and classical heating

Microwave irradiation was applied to the synthesis of polyethers from 1,8‐dibromo‐ and 1,8‐dimesyl‐octane under solid–liquid phase‐transfer catalytic conditions. To evaluate the influence of microwaves on the reaction rates and polyether properties, we carried out the polymerization reactions under similar conventional conditions (oil bath) with the same temperature profiles. First, the microwave‐assisted syntheses proceeded more rapidly in comparison with conventional heating, and the reaction time was reduced from 24 h to 30 min with higher yields of polyethers. Second, the structure of the polymers strictly depended on the activation mode. Under microwave conditions, the polyethers were characterized by higher molecular weights with better homogeneity. Third, the mechanism of chain termination was different under microwave and conventional conditions. The polyethers prepared with conventional heating possessed shorter chains with mainly hydroxylated ends, whereas under microwave irradiation, the polymer chains were longer with mainly ethylenic group ends. In fact, under microwave irradiation, ethylenic group ends were formed rather rapidly and set up a hindrance to further polymer growth. In contrast, under conventional conditions terminations were essentially constituted by hydroxyl functions; however, further polymerization was terminated as well. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 1255–1266, 2003     

微波在聚合物科学中的应用

综述了聚合物科学中微波应用的研究进展,讨论了微波在聚合物合成中的研究概况。也介绍了聚合物微波加工的原理及对材料结构与性能的影响,一方面微波在树脂固化中得到广泛的应用;另一方面微波在橡胶硫化中也取得了较大的成功。另外也介绍了微波在聚合物改性方面的应用。最后指出目前存在的一些问题。